Interferon-gamma and tumor necrosis factor-alpha synergistically enhance the immunosuppressive capacity of human umbilical-cord-derived mesenchymal stem cells by increasing PD-L1 expression

Figure 6 Synergy by IFN-γ and tumor necrosis factor-alpha enhanced the immunosuppressive capacity of human umbilical-cord-mesenchymal stem cells by inducing programmed cell death protein 1 ligand expression. A: The CFSE fluorescence intensity of CFSE-labeled peripheral blood mononuclear cells (PBMCs) was detected after co-culture with human umbilical-cord-mesenchymal stem cells (hUC-MSCs) with different treatments for 3 d. The CFSE fluorescence intensity of CD3-positive PBMCs on day 0 was used as the reference (1.29%). The histogram shows the quantification results pertaining to the mean fluorescent intensity of CFSE in each group; B: Schematic diagram of dextran sulfate sodium-induced colitis and MSCs transplantation therapy in mice; C: Bodyweight of mice in each group during the disease process (n = 6); D: Macroscopic appearance of the colon in each group; E: Colon sections embedded in paraffin were stained with hematoxylin and eosin for light microscopy assessment. Scale bar, 50 μm; F: Histopathological score of colons from each group was assessed for disease severity (n = 3); G: Infiltration cells expressing CD4 or CD11b in colon tissue sections from each group were analyzed by immunohistochemical staining (n = 3). Scale bar, 50 μm; H: Myeloperoxidase activity in the colon was determined (n = 3); I: The colonic mRNA expression of Treg (Foxp3) from each group were analyzed by quantitative real-time PCR (n = 3); J: Levels of inflammatory factors in colon tissue homogenates from each group were determined using ELISA (n = 3). IT-MSCs refer to hUC-MSCs pretreated with IFN-γ and tumor necrosis factor-alpha for 24 h. C: Control; ^aP < 0.01; ^bP < 0.001; ^cP < 0.0001; ^dP > 0.05.